1Human Evolutionary Biology, Harvard University, 2Harvard University Center for the Environment, Harvard University
Saturday 3:15-3:30, Ballroom A
The majority of primate parasites are generalists, meaning that they infect multiple species of primates or other animals. Hence, the community of hosts found at a site is expected to impact parasitism. Two main non-null effects are possible. In some cases, we might find an “amplification effect,” with higher levels of parasitism in richer primate communities. In other cases, we expect a “dilution effect,” with reductions in parasitism in richer primate communities due to the existence of less competent hosts that fail to transmit the infection. We investigated these possibilities using the Global Mammal Parasite Database. In analyses of prevalence at different sites, we found some evidence for associations between parasitism and mammalian or primate richness at a site, with a mixture of positive and negative effects. When examining range overlap at the host species level, we found stronger evidence for amplification effects: parasite richness covaried positively with the number of overlapping primates and degree of range overlap. Finally, in a meta-analysis of 16 studies at 12 study areas, we found a very weak effect of disturbance to increase parasitism. Assuming that more disturbed habitats have lower host diversity, this weak positive effect is consistent with a dilution effect, but only approached significance. Thus, using data compiled at multiple scales, our findings were generally most consistent with weak amplification effects. However, we found clear heterogeneity in effects depending on host, parasite and environmental characteristics. An important goal for research moving forward is to understand the drivers of this variation.